Various types of closures are presently used by the bottling industry. One commonly used closure is an internally threaded cap which is screwed over an externally threaded bottle. This simple closure is used when the bottler's primary requirement is providing the consumer with a readily reusable container. Another type of closure is made from a membrane which can be adhered by heat or fusion bonding to the lip of the container's mouth. This closure is found on single-use containers often where protection from tampering is desired. Combining the sealable membrane with the screw cap offers the bottler a reusable tamper-proof container.
A recognized problem with the reusable tamper-proof container is that the closure is often difficult to remove from the bottle. Various methods have been used to aid in the "peelability" of the closure, but none have been found entirely successful. The wall thickness of the bottle's neck can be locally reduced at the junction of the closure and the bottle either partially or entirely around the lip of the bottle. This provides a small area by which the closure can be grasped and then pulled or pushed off the container. In this case the closure chosen by the bottler may either have a thin or thick membrane depending on his requirements. Of the two, the thicker membrane is generally sturdier and thus easier to remove. But because it is sturdier, upon removal the closure often remains completely intact. The closure can then be placed back on the bottle to create the false impression of an untampered seal. The use of a thin or weaker membrane avoids this problem since it is generally destroyed when removed, but complete removal is much more difficult because of its tendency to tear and its limited grasping area.